Radiative energy loss of relativistic charged particles in absorptive media

We determine the energy loss spectrum per time-interval of a relativistic charge traversing a dispersive medium. Polarization and absorption effects in the medium are modelled via a complex index of refraction. We find that the spectrum amplitude becomes exponentially damped due to absorption mechanisms. Taking explicitly the effect of multiple scatterings on the charge trajectory into account, we confirm results obtained in a previous work.